Morphological Complexity as a Floral Signal: From Perception by Insect Pollinators to Co-Evolutionary Implications

Krishna, Shivani; Keasar, Tamar

doi:10.3390/ijms19061681

Cited by 43 publications

(34 citation statements)

References 130 publications

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“…However, our results show that a rare plant species may persist in competition with a more common one if the rare plant has more complex flowers. Our results are in agreement with previous empirical research (reviewed in Krishna & Keasar, 2018), suggesting that foragers displayed stronger specialization when visiting plant species with more complex flowers (Heinrich, 1976(Heinrich, , 1979Laverty, 1994aLaverty, , 1994bStout et al, 1998) and that among self-incompatible species, rare flowers have more restricted floral access (or higher complexity) than their common counterparts (Kunin & Shmida, 1997).…”

Section: Discussionsupporting

confidence: 92%

Floral complexity can help maintain plant diversity by inducing pollinator specialization

Gurevich

Hadany

2021

Journal of Ecology

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Ecological studies have widely demonstrated that plant diversity positively affects ecosystem functioning and ability to respond to changing conditions (Hooper & Vitousek, 1997;Isbell et al., 2011). As most flowering plants are pollinated by animals, plant-pollinator interactions play a significant role in the health of terrestrial ecosystems (Klein et al., 2007;Ollerton et al., 2011). The stable coexistence of multiple species in plant communities requires explanation, as many plants compete for resources such as water, light, soil nutrients and pollinators (Barot & Gignoux, 2004;Rathcke, 1983). Various factors can contribute to plant coexistence (Wilson, 2011). Flowering plants may mitigate competition, for example, by forming spatial patches (Tilman, 1982), by temporal heterogeneity in resource consumption (Questad & Foster, 2008) or by pollination niche partitioning (Benadi, 2015;Pauw, 2013). Recent theoretical papers have integrated the foraging behaviour of pollinators with plant community dynamics and discussed factors that could allow plant coexistence: adaptive foraging behaviour of individual pollinators (Revilla & Křivan, 2016;Song & Feldman, 2014); high immigration rate of a rare plant species (Song & Feldman, 2014); pollen carryover (Montgomery, 2009;Song & Feldman, 2014); and dynamics of floral reward production and limited information of pollinators regarding reward distribution (Benadi & Gegear, 2018).The effects of pollinators' foraging behaviour on plant coexistence may also be mediated by floral traits, such as complex flower morphology. Morphological complexity (Figure 1) can have conflicting effects on the plant and on the pollinator during a visit: it tends to be beneficial for the plant, since it encourages longer visits and thus potentially increased pollen transfer (Harder, 1990;Manetas &

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Section: Discussionsupporting

confidence: 92%

Floral complexity can help maintain plant diversity by inducing pollinator specialization

Gurevich

Hadany

2021

Journal of Ecology

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“…Such flowers are common in numerous plant families, for example Fabaceae, Orchidaceae, and Lamiaceae (Krishna and Keasar, 2018). In other plants, the complexity of flower handling involves finding the high-rewarding nectaries out of several available ones (as in some mustards) or sonicating the anthers to access their pollen (as in several Solanaceae species).…”

Section: Introductionmentioning

confidence: 99%

Generalization of Foraging Experience Biases Bees Toward Flowers With Complex Morphologies

Krishna

Keasar

2021

Front. Ecol. Evol.

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The importance of pollinators as selective agents for many floral traits is well established, but understanding their role in the evolution of complex floral shapes remains challenging. This is because pollinators often need much practice to efficiently handle morphologically complex flowers and extract their food rewards. What induces foragers to persistently visit and pollinate complex flowers despite their initial low profitability? We previously found that naive bumblebees, and unsuccessful feeding attempts of experienced ones, contribute to the pollination of complex flowers. Here we tested a complementary hypothesis, positing that successful foraging on flowers of one complex shape prepares pollinators to visit other species of different complex morphologies. We trained bumblebees to computer-controlled artificial flowers that were either simple, complex or both simple and complex. We then recorded their feeding choices and handling times on a second array of simple and complex flowers that had different shapes and required another handling technique. Bees trained on a single flower type (whether simple or complex) preferred flowers of the same type in the testing array. The foragers’ preferences after training on both flower types depended on the reward schedule during training: when both flower types rewarded equally, simple flowers were preferred at the test phase; when complex flowers provided higher reward during training, they became the preferred flower type during testing. These results suggest that successful foraging on complex flowers, especially when highly rewarding, can indeed induce insect pollinators to attempt additional flower species with other complex shapes.

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“…Bees generally take longer to learn to extract resources from flowers that require complex handling behaviours than those that do not (Gegear and Laverty 1998), but bees can remember flower-handling techniques for long time periods (Keasar et al 1996, Chittka andThomson 1997). Thus, if simple and complex flowers contain similar resources and are equally abundant, it is initially more costly for bees to visit flowers that require complex handling behaviours until these behaviours can be performed efficiently (Krishna and Keasar 2018). The low visitation rates to C. hyacinthoides when their relative abundances are low might thus potentially be attributed to costs associated with learning to handle a rare and complex flower type.…”

Section: High Availability Of Other Pollen Sources Is Associated With Less Buzz Pollinationmentioning

confidence: 99%

Reduced visitation to the buzz-pollinated Cyanella hyacinthoides in the presence of other pollen sources in the hyperdiverse Cape Floristic Region

Kemp

Telles

Vallejo-Marin

2021

Preprint

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Many plant species have floral morphologies that restrict access to floral resources, such as pollen or nectar, and only a subset of floral visitors can perform the complex handling behaviours required to extract restricted resources. Due to the time and energy required to extract resources from morphologically complex flowers, these plant species potentially compete for pollinators with co-flowering plants that have more easily accessible resources. A widespread floral mechanism restricting access to pollen is the presence of tubular anthers that open through small pores or slits (poricidal anthers). Some bees have evolved the capacity to remove pollen from poricidal anthers using vibrations, giving rise to the phenomenon of buzz-pollination. These bee vibrations that are produced for pollen extraction are presumably energetically costly, and to date, few studies have investigated whether buzz-pollinated flowers may be at a disadvantage when competing for pollinators' attention with plant species that present unrestricted pollen resources. Here, we studied Cyanella hyacinthoides (Tecophilaeaceae), a geophyte with poricidal anthers in the hyperdiverse Cape Floristic Region of South Africa, to assess how the composition and relative abundance of flowers with easily accessible pollen affect bee visitation to a buzz-pollinated plant. We found that the number of pollinator species was not influenced by community composition. However, visitation rates to C. hyacinthoides were negatively related to the abundance of flowers with more accessible resources. Visitation rates were strongly associated with petal colour, showing that flower colour is important in mediating these interactions. We conclude that buzz-pollinated plants might be at a competitive disadvantage when many easily accessible pollen sources are available, particularly when competitor species share its floral signals.

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Morphological Complexity as a Floral Signal: From Perception by Insect Pollinators to Co-Evolutionary Implications

Cited by 43 publications

References 130 publications

Floral complexity can help maintain plant diversity by inducing pollinator specialization

Floral complexity can help maintain plant diversity by inducing pollinator specialization

Generalization of Foraging Experience Biases Bees Toward Flowers With Complex Morphologies

Reduced visitation to the buzz-pollinated Cyanella hyacinthoides in the presence of other pollen sources in the hyperdiverse Cape Floristic Region

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